1. Field of the Invention
This invention relates to a reference beam detector that can easily detect a rotary laser projecting apparatus such as a laser level or some other laser projecting apparatus.
2. Prior Art
Laser projecting apparatus, rotary laser projecting apparatus in particular, are widely used to provide a reference level in the field of civil engineering and building. A rotary laser projecting apparatus is used to provide a reference plane or a reference level by emitting a laser beam that rotates horizontally. When a rotary laser projecting apparatus is made to emit a laser beam vertically, a horizontal reference position can be determined by the plane defined by the laser beam.
A rotary laser projecting apparatus is mostly used in combination with a beam detector in actual applications including those for leveling the foundation in house building operations, those for leveling window frames and plugs in interior works and those for leveling the ground in civil engineering construction works.
On the site of using a rotary laser projecting apparatus for a construction work, it is normally placed on a tripod and regulated to emit a laser beam always on an imaginary horizontal plane. As shown in FIG. 11 of the accompanying drawings, a beam detector 10 comprises a detector main body 12 for receiving a reference beam and an index unit 14 rigidly secured to a lateral side of the detector main body.
When using such a rotary laser projecting apparatus and a beam detector 10, the laser beam emitted from the rotary laser projecting apparatus that is supported at a predetermined level by a tripod is received by the laser beam detector 10 that is typically arranged on a wall to define a reference point, which is marked on the wall by means of the index unit 14 and a pencil. Then, positions necessary for the construction work are marked by way of the reference point; for example, a point 3 cm above the reference point, a point 20 cm below the reference point and so on. A measure and a marker are normally used for marking a position by referring to the reference point.
The height of the tripod may often have to be modified in order to make the rotary laser projecting apparatus get to a predetermined level.
The operation of modifying the height of the tripod can be performed efficiently when the tripod is equipped with a level shifter.
While a tripod equipped with a level shifter operates relatively reliably for shifting the level of the rotary laser projecting apparatus supported by the tripod, a finely regulating operation will normally have to be conducted on it after shifting the level of the rotary laser projecting apparatus. Additionally, a tripod provided with a level shifter is rather costly.
The operation of modifying the height of a tripod in fact consists in redoing the operation of setting up the tripod. After completing the operation of modifying the height of the tripod, a finely regulating operation will have to be conducted once again. Thus, a given series of operations have to be repeated each time the height of the tripod is modified regardless if the tripod is equipped with a level shifter or not. Therefore, the operation of modifying the height of a tripod is cumbersome, inaccurate and inefficient.
While the use of a marker may be convenient for marking positions located close by relative to each other, a number of markers will have to be provided for marking remote positions. Additionally, the operation of marking remote positions is time consuming and costly.
In view of the above identified problems of known reference beam detectors, therefore, it is an object of the present invention to provide a reference beam detector that can be used to accurately and efficiently perform a level shifting operation. Another object of the present invention is to provide a beam detector that can effectively eliminate the use of markers and other devices that are structurally simple but entail cumbersome operations and also the use of a level shifter.